KR20080072226A - Apparatus and method for reproducing optical disk - Google Patents

Abstract

An apparatus and a method for reproducing an optical disk are provided to check signal quality based on reproducing frequency deviation of the optical disk and on an increase/decrease in RPM(Revolution Per Minute) of a spindle motor so as to filter a signal effectively and prevent degradation of the signal. An apparatus for reproducing an optical disk comprises a pickup part(210), a signal converter(220), an amplifier(230), an equalizer(240), a control part(250), and a signal processor(260). The control part includes a judging part(252), a signal quality checking part(254), and a section determining part(256). The judging part checks whether an inserted optical disk belongs to a new kind. The signal quality checking part checks signal quality based on reproducing frequency deviation of the optical disk by measuring the signal quality with increasing and decreasing RPM of a spindle motor based on the present frequency. The section determining part determines how many areas the optical disk is divided into.

Description

Apparatus and method for reproducing optical disk

1 is a block diagram showing a conventional optical disc reproducing apparatus.

2 is a block diagram showing an optical disk reproducing apparatus according to an embodiment of the present invention.

3 is a reference diagram illustrating a signal quality deviation according to a reproduction frequency deviation according to an embodiment of the present invention.

4 is a flowchart showing an optical disk reproducing method according to an embodiment of the present invention.

5 is a flowchart illustrating an optical disk reproducing method according to an embodiment of the present invention.

6 is a flowchart showing an optical disk reproducing method according to another embodiment of the present invention.

The present invention relates to an optical disk reproducing apparatus and method.

1 is a block diagram showing a conventional optical disc reproducing apparatus.

Referring to Fig. 1, in reproducing data recorded on an optical disc, the data is picked up by the pickup unit 110 and then converted into an electrical signal by the signal converter 120. This electrical signal is an RF (Radio Frequency) signal. The RF signal is amplified by the amplification unit 130 to appropriately amplify the signal level according to noise removal and double speed. The characteristics of the data recorded on the optical disc can be varied for various reasons, which may cause the RF signal, which is an electrical signal, to deviate from the normal level, thereby distorting the reproduction signal. In order to solve such a problem, the equalizer 140 filters the distorted RF signal. The controller 150 determines a cut-off frequency to be filtered.

Determine and provide this to the equalizer 140.

The quality of the signal varies depending on the position of the optical disk. However, there is a problem in that it is not possible to filter the RF signal properly according to various types of optical disks and the signal quality thereof. In addition, measuring signal quality has caused additional system loads in addition to the system related to the regeneration operation, which leads to problems of system complexity and increased power consumption.

It is therefore an object of the present invention to solve the above problems, to provide an optical disk reproducing apparatus and method for efficiently filtering signals in accordance with signal quality.

In addition, an object of the present invention is to perform appropriate filtering for each region to prevent deviation of signal quality and signal degradation.

According to an aspect of the present invention, in an optical disc reproducing apparatus for equalizing and reproducing an optically picked up signal from an optical disc, the optical disc is divided into several regions according to a reproduction frequency deviation corresponding to a signal quality deviation to be limited. A control unit to determine whether or not; And an equalizer for performing filtering on signals picked up optically from the determined plurality of regions at a cutoff frequency corresponding to the reproduction frequency deviation.

The control unit may include: a signal quality determining unit which determines a signal quality according to a reproduction frequency deviation of the optical disc; And an area determining unit which receives a signal quality deviation to be restricted from the outside and determines how many areas to divide the optical disc according to the reproduction frequency deviation corresponding to the signal quality deviation.

The signal quality grasping unit may identify signal quality deviations according to a plurality of different reproduction frequency deviations, and obtain a polynomial for signal quality deviations according to the reproduction frequency deviations.

The signal quality grasping unit may determine signal quality deviations according to N + 1 different reproduction frequency deviations, and obtain an Nth order polynomial for signal quality deviations according to the reproduction frequency deviations.

It is preferable that the signal quality grasping unit grasps the signal quality deviation according to the reproduction frequency deviation by moving the reproduction position.

Preferably, the signal quality grasping unit grasps the signal quality variation according to the reproduction frequency variation by changing the speed of the motor driving the optical disc.

The signal quality grasping unit preferably grasps jitter according to a reproduction frequency deviation of the optical disc.

The jitter deviation detected by the signal quality grasping unit is preferably proportional to the reproduction frequency deviation of the optical disc.

Preferably, the signal quality grasping unit grasps a bER (bit error rate) according to a reproduction frequency deviation of the optical disc.

에 의해서 상기 영역의 개수를 정하되, 여기서, a는 상기 광 디스크의 최내주와 최외주에서의 재생 주파수 차이이며, n은 상기 영역의 개수인 것이 바람직하다.The area determiner

The number of the regions is determined by A, wherein a is a difference between reproduction frequencies at the innermost and outermost circumferences of the optical disk, and n is the number of the regions.

Preferably, the area determining unit determines how many areas the optical disc is divided into and the boundaries of the divided areas.

The control unit may further include a determination unit that determines whether it is necessary to newly determine an area of the optical disk filtered by another cutoff frequency, and the signal quality determination unit and the area determination unit need to determine the area newly by the determination unit. It is preferable to operate when there is.

Preferably, the cutoff frequencies corresponding to the reproduction frequency deviations have different values in the determined plurality of regions.

The cutoff frequency corresponding to the reproduction frequency deviation may have the same value in a region where reproduction frequency deviations are similar among the determined plurality of regions.

It is preferable that regions having similar reproduction frequency deviations do not adjoin each other.

Preferably, the equalizer performs low pass filtering at different cutoff frequencies on signals optically picked up from the determined plurality of regions.

According to another aspect of the present invention, there is provided an optical disk reproducing method for equalizing and reproducing an optically picked up signal from an optical disk. Determining whether to divide into regions; And filtering the cut-off frequency corresponding to the reproduction frequency deviation with respect to the determined plurality of regions.

Prior to determining the number of areas to divide the optical disk, it is preferable to further include the step of determining the signal quality according to the reproduction frequency deviation of the optical disk.

In the signal quality determining step, it is preferable to obtain a polynomial of signal quality deviations according to the reproduction frequency deviations by identifying signal quality deviations according to a plurality of different reproduction frequency deviations.

In the signal quality determining step, it is preferable to obtain signal N deviations according to N + 1 different reproduction frequency deviations and obtain an Nth order polynomial for signal quality deviations according to the reproduction frequency deviations.

In the signal quality grasping step, it is preferable to grasp the signal quality deviation according to the reproduction frequency deviation by moving the reproduction position.

In the signal quality determining step, it is preferable to determine the signal quality deviation according to the reproduction frequency deviation by changing the speed of the motor driving the optical disc.

In the signal quality determining step, it is preferable to determine jitter according to the reproduction frequency deviation of the optical disc.

It is preferable that the deviation of jitter detected by the signal quality determining step is proportional to the reproduction frequency deviation of the optical disc.

In the signal quality determining step, it is preferable to determine a bit error rate (bER) according to the reproduction frequency deviation of the optical disc.

에 의해서 상기 영역의 개수를 정하되, 여기서, a는 상기 광 디스크의 최내주와 최외주에서의 재생 주파수 차이이며, n은 상기 영역의 개수인 것이 바람직하다.The area determination step is

The number of the regions is determined by A, wherein a is a difference between reproduction frequencies at the innermost and outermost circumferences of the optical disk, and n is the number of the regions.

The area determining step preferably determines the number of areas divided in the optical disk and the boundary of the divided areas.

The method may further include determining whether it is necessary to newly determine an area of the optical disk filtered by different cutoff frequencies before the signal quality determining step, wherein the signal quality determining step and the area determining step include the determining step. It is preferable to carry out when it is necessary to newly determine the area by.

Preferably, the cutoff frequencies corresponding to the reproduction frequency deviations have different values in the determined plurality of regions.

The cutoff frequency corresponding to the reproduction frequency deviation may have the same value in a region where reproduction frequency deviations are similar among the determined plurality of regions.

It is preferable that regions having similar reproduction frequency deviations do not adjoin each other.

In the filtering step, it is preferable to perform low pass filtering at different cutoff frequencies on signals picked up optically from the determined plurality of regions.

The technical problem is a computer-readable recording medium having a program for executing an optical disc reproducing method of equalizing and reproducing an optically picked up signal from an optical disc, wherein the method corresponds to a reproduction corresponding to a signal quality deviation to be restricted. Determining how many areas to divide the optical disc according to frequency deviations; And performing filtering on the determined plurality of regions at a cut-off frequency corresponding to the reproduction frequency deviation.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram showing an optical disk reproducing apparatus according to an embodiment of the present invention.

2, an optical disc reproducing apparatus according to an embodiment of the present invention includes a pickup unit 210, a signal converter 220, an amplifier 230, an equalizer 240, a controller 250, and a signal processor. 260, and the controller 250 includes a determiner 252, a signal quality determiner 254, and an area determiner 256.

The pickup unit 210 scans a laser onto the optical disk surface and receives the reflected signal. The picked-up signal is converted into an RF signal by the signal converter 220 and amplified by the amplifier 130.

The determination unit 252 of the control unit determines whether the inserted optical disc is a new type of optical disc. In other words, it is determined whether the area of the optical disk needs to be newly determined. Depending on the quality of the reproduction signal, the number of divided regions and the boundary of the regions must be different, and the disc to be inserted determines whether these regions should be newly determined.

The signal quality grasping unit 254 grasps the signal quality according to the reproduction frequency deviation of the optical disc. For this purpose, the signal quality should be measured while changing the reproduction frequency deviation. There are methods for changing the reproduction frequency deviation, such as changing the reproduction position or adjusting the motor speed. For example, the signal quality is measured while increasing the revolution per minute (RPM) of the spindle motor by a certain amount at regular intervals and decreasing by a certain amount at regular intervals. Signal quality is measured by measuring jitter or bit error rate (bER). Based on the measured signal quality, it is possible to derive the Nth order polynomial for the reproduction frequency deviation and the signal quality deviation. In order to obtain the Nth order polynomial, the signal quality deviation value with respect to the N + 1 reproduction frequency deviations may be measured. Based on this polynomial, the reproduction frequency deviation according to the signal quality deviation to be maintained in the current system can be obtained.

The area determiner 256 receives the signal quality deviation to be restricted from the outside, and determines how many areas the optical disc is divided according to the reproduction frequency deviation corresponding to the signal quality deviation. According to the region determined by the region determiner 256, the equalizer 240 performs filtering at a cutoff frequency corresponding to the reproduction frequency deviation for each region.

For example, assuming that the difference between the reproduction frequencies is a times at the innermost and outermost circumferences at variable speed reproduction, the number of regions for which the cutoff frequency of the equalizer 240 can be set is n, and the reproduction frequency of the innermost race is When f is the deviation of the reproduction frequency obtained from the polynomial, the following equation holds.

Therefore, the number n of regions is as follows.

By using the number n of these regions and the reproduction frequency deviation f, the frequency which becomes the boundary of an area can be calculated | required, and the position can also be detected. The boundary reproduction frequency and position of the region are shown in Table 1, and since the region number n is the last region, the boundary reproduction frequency and position information are not necessary.

Area number Boundary refresh frequency location Cutoff frequency  One

 P_1  F_1  2

 P-2  F_2  ...  ...  P_3  F_3  n-1

 P_n-1  F_n-1  n  _  _  F_n

The table as described above may be derived by the signal quality determiner 254 and the region determiner 256. Since the above values can be changed by the system or externally limited quality deviation, the value changes when increasing or decreasing the limiting signal quality deviation, but changes the limited quality deviation in the same system or the same type of disk. In this case, it can be updated by a table or polynomial without having to measure the signal quality again.

The equalizer 240 filters the signals picked up from the plurality of regions determined by the region determiner 256 with a cutoff frequency corresponding to the reproduction frequency deviation. That is, filtering is performed at different cutoff frequencies according to areas, and when filtering reaches a set area switching position, the filtering is performed by changing the cutoff frequency of the equalizer 240 to a cutoff frequency corresponding to the area. do. As a result, a signal whose signal quality is kept constant can be reproduced. The filtering performed by equalizer 240 is primarily low pass filtering.

The cutoff frequency corresponding to the reproduction frequency deviation may have different values in the plurality of determined regions, or may have the same value in the region where the reproduction frequency deviations are similar. For example, if the reproduction frequency deviations are the same in non-adjacent regions, the same cutoff frequency may be filtered.

The signal processor 260 demodulates and error corrects the RF signal filtered by the equalizer 240 to generate digital data processed into a digital signal.

3 is a reference diagram illustrating a signal quality deviation according to a reproduction frequency deviation according to an embodiment of the present invention.

The signal quality determining unit 254 measures the signal quality as the frequency deviation of the reproduction signal is changed. FIG. 3 illustrates jitter deviation according to the reproduction frequency deviation by measuring jitter. Based on 38MHz, the jitter deviation was measured with a + -15% deviation, which can be seen as a second order polynomial. In order to obtain the second order polynomial, jitter is measured according to the reproduction frequency deviation at three positions. The graph of FIG. 3 is as follows.

The x axis shows the frequency deviation of the RF reproduction signal, and the y axis shows the jitter deviation. If the jitter deviation is determined by the above graph or equation (3), the RF reproduction frequency deviation can be obtained. If the difference between the innermost and outermost reproduction frequencies is 2.4 times, the number of regions can be obtained by the equation (2). The following table shows the reproduction frequency deviation and the number of regions according to the jitter deviation.

Jitter deviation (y) Playback frequency deviation (x) Number of zones 0.1% 3.50% 26 0.5% 7.79% 12 1.0% 11.01% 9

If the innermost reproduction frequency is 78.48Mbps and the jitter deviation is limited to 0.1%, the result shown in Table 3 can be obtained. The value of the boundary reproduction frequency can be obtained by the boundary reproduction frequency equation of Table 1.

Area number Boundary reproduction frequency (Mbps) The location of the boundary Cutoff frequency One 81.2268 P_1 F_1 2 84.0697 P_2 F_2 ... ... ... ... 25 185.467 P_25 F_25 26 - F_26

If the jitter deviation is limited to 0.5%, the number of regions can be set to 12 according to Table 2, and the boundary reproduction frequency is shown in Table 3 below.

Area number Boundary reproduction frequency (Mbps) The location of the boundary Cutoff frequency One 84.5936 P_1 F_1 2 91.1834 P_2 F_2 ... ... ... ... 11 179.111 P_11 F_11 12 - - F_12

If we limit the jitter deviation to 1.0%, we get the results in Table 5. The number of zones can be set to nine and the number of cutoff frequencies accordingly is nine.

Area number Boundary reproduction frequency (Mbps) The location of the boundary Cutoff frequency One 87.1206 P_1 F_1 2 96.7126 P_2 F_2 ... ... ... ... 8 181.99 P_8 F_8 9 _ _ F_9

The cutoff frequency value to be set in each case can be determined by adjusting appropriately in each area.

4 is a flowchart showing an optical disk reproducing method according to an embodiment of the present invention.

In step 410, the signal quality deviation to be restricted is received from the outside. Signal quality may include jitter or bER. The signal quality deviation may be input from the user of the apparatus, but may be set inside the optical disc reproducing apparatus by the designer. Receiving the signal quality deviation is to obtain the reproduction frequency deviation according to the signal quality deviation, thereby distinguishing the areas according to the signal quality in the optical disc.

In step 420, it is determined how many areas of the optical disc are divided according to the reproduction frequency deviation corresponding to the signal quality deviation. For this purpose, the measurement of signal quality deviation due to reproduction frequency deviation should be prioritized. After determining the reproduction frequency deviation in accordance with the signal quality deviation to be limited, the number of areas of the optical disc can be determined according to the reproduction frequency deviation. The number of regions can be obtained according to Equations 1 and 2 below.

In operation 430, filtering is performed on each of the plurality of regions determined in operation 420 at a cutoff frequency corresponding to the reproduction frequency deviation. Since the signal quality is different for each region, it is necessary to perform filtering at an appropriate cutoff frequency. The filtering performed is mainly low pass filtering. The cutoff frequency corresponding to the reproduction frequency deviation may have different values in the plurality of determined regions, or may have the same value in the region where the reproduction frequency deviations are similar. For example, if the reproduction frequency deviations are the same in non-adjacent regions, the same cutoff frequency may be filtered.

5 is a flowchart illustrating an optical disk reproducing method according to an embodiment of the present invention.

In step 510, it is determined whether a pre-test is necessary before playing the optical disc. The pretest is about how to divide the optical disk into how many regions, how to define the boundary of the region, and what to set the value of the cutoff frequency according to the region. It can be determined that the optical disc inserted in the optical disc reproducing apparatus is a new type of optical disc, or a pretest is necessary when the reproducing apparatus requires a new setting. However, if the signal quality deviation is to be set differently in the same type of optical disc, the pre-test is not necessary because the result of the test (the relationship between the reproduction frequency deviation and the signal quality deviation) already stored is updated.

In step 520, if it is determined that a pre-test is necessary, the signal quality according to the reproduction frequency deviation is determined. To do this, it is necessary to measure the signal quality by playing the disc at a plurality of positions. There may be jitter or bER in the signal quality being measured. By identifying a plurality of signal qualities, it is possible to obtain a polynomial for the signal quality variance according to the reproduction frequency deviation. For example, if a signal quality measurement is made at the N + 1 position, the Nth order polynomial can be obtained based on this.

In step 530, the signal quality deviation to be limited is received from the outside. The signal quality deviation may be input from the user of the apparatus, but may be set inside the optical disc reproducing apparatus by the designer. The number varies in the divided areas according to the signal quality deviation to be limited. The larger the signal quality deviation, the smaller the number of regions.

In step 540, it is determined how many areas of the optical disc are divided according to the reproduction frequency deviation corresponding to the signal quality deviation. When the signal quality according to the reproduction frequency deviation is determined in operation 520, a relational expression between the reproduction frequency deviation and the signal quality may be obtained, and the reproduction frequency deviation corresponding to the signal quality deviation to be limited may be obtained. When the obtained reproduction frequency deviation is applied to Equation 2, the number of regions to be divided can be determined, and the position of the boundary of the region can be grasped according to Table 1.

In operation 550, filtering is performed at different cutoff frequencies for each of the plurality of regions. Since the signal quality varies from region to region, it is necessary to perform filtering at an appropriate cutoff frequency. In other words, while filtering the signal picked up from the optical disc, the filtering should be performed by changing to the cutoff frequency corresponding to the area when passing the boundary of the area identified in step 540. If the pre-test of step 510 is not necessary, filtering is performed in step 550 without going through steps 520 to 540 of determining the number of areas of the optical disc.

6 is a flowchart showing an optical disk reproducing method according to another embodiment of the present invention.

In operation 610, the optical disk is divided into a plurality of areas. The optical disc may be divided based on the reproduction frequency deviation or the like.

In operation 620, the plurality of divided regions are filtered at a predetermined cutoff frequency. The predetermined cutoff frequency is different in the adjacent region. In the case where the reproduction frequency deviation is divided based on the reproduction frequency deviation, adjacent regions are different in reproduction frequency deviation from each other, and thus filtering using a different value as the cutoff frequency.

Meanwhile, the above-described embodiments of the present invention can be written as a program that can be executed in a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium.

The computer-readable recording medium may be a magnetic storage medium (for example, a ROM, a floppy disk, a hard disk, etc.), an optical reading medium (for example, a CD-ROM, a DVD, etc.) and a carrier wave (for example, the Internet). Storage medium).

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

According to the present invention as described above, there is provided an optical disk reproducing apparatus and method for efficiently filtering signals in accordance with signal quality.

In addition, appropriate filtering may be performed for each region to prevent deviation of signal quality and signal degradation.

Claims (33)

An optical disc reproducing apparatus for equalizing and reproducing a signal picked up optically from an optical disc, A control unit which determines how many regions the optical disc is divided according to the reproduction frequency deviation corresponding to the signal quality deviation to be limited; And And an equalizer for filtering the signals optically picked up from the determined plurality of regions by a cutoff frequency corresponding to the reproduction frequency deviation. The method of claim 1, The control unit, A signal quality determining unit which determines a signal quality according to a reproduction frequency deviation of the optical disc; And And a region determination unit which receives a signal quality deviation to be restricted from the outside and decides how many areas to divide the optical disk according to the reproduction frequency deviation corresponding to the signal quality deviation. The method of claim 2, And the signal quality determining unit detects signal quality deviations according to a plurality of different reproduction frequency deviations, and obtains a polynomial for signal quality deviations according to the reproduction frequency deviations. The method of claim 3, And the signal quality determining unit detects signal quality deviations according to N + 1 different reproduction frequency deviations, and obtains an Nth order polynomial for signal quality deviations according to the reproduction frequency deviations. The method of claim 3, And the signal quality grasping unit grasps the signal quality variation according to the reproduction frequency deviation by moving the reproduction position. The method of claim 3, And the signal quality grasping unit grasps the signal quality deviation according to the reproduction frequency deviation by changing the speed of the motor driving the optical disc. The method of claim 2, And the signal quality grasping unit grasps jitter or bit error rate according to a reproduction frequency deviation of the optical disc. The method of claim 7, wherein And the deviation of the jitter detected by the signal quality determining unit is proportional to the reproduction frequency deviation of the optical disc. The method of claim 2, The area determiner

Wherein the number of the areas is determined, wherein a is a difference between reproduction frequencies at the innermost and outermost circumferences of the optical disc, and n is the number of the areas. The method of claim 2, And the area determining unit determines how many areas the optical disc is divided into and the boundaries of the divided areas. The method of claim 2, The control unit may further include a determination unit determining whether it is necessary to newly determine an area of the optical disk filtered by another cutoff frequency. And the signal quality determining unit and the area determining unit operate when the determining unit needs to newly determine the area. The method according to claim 1 or 2, And a cutoff frequency corresponding to the reproduction frequency deviation has different values in the determined plurality of regions. The method according to claim 1 or 2, And a cutoff frequency corresponding to the reproduction frequency deviation has the same value in a region in which reproduction frequency deviations are similar among the determined plurality of regions. The method of claim 13, And the regions in which the reproduction frequency variations are similar are not adjacent to each other. The method according to claim 1 or 2, And the equalizer performs low pass filtering at different cutoff frequencies on signals picked up optically from the determined plurality of regions. An optical disc reproducing method for equalizing and reproducing a signal picked up from an optical disc, Determining how many regions the optical disc is to be divided according to the reproduction frequency deviation corresponding to the signal quality deviation to be limited; And And performing filtering on the determined plurality of regions at a cut-off frequency corresponding to the reproduction frequency deviation. The method of claim 16, And determining the signal quality according to the reproduction frequency deviation of the optical disc before determining how many areas to divide the optical disc into. The method of claim 17, The signal quality determining step is characterized in that the signal quality deviations according to a plurality of different reproduction frequency deviations are grasped to obtain a polynomial for the signal quality variation according to the reproduction frequency deviations. The method of claim 18, The signal quality determining step is characterized in that the signal quality deviation according to the N + 1 different reproduction frequency deviations is obtained, and an Nth order polynomial for the signal quality variation according to the reproduction frequency deviation is obtained. The method of claim 17, The signal quality identifying step is characterized in that for detecting the signal quality deviation in accordance with the reproduction frequency deviation by moving the reproduction position. The method of claim 18, And the signal quality determining step determines the signal quality deviation according to the reproduction frequency deviation by changing the speed of the motor driving the optical disc. The method of claim 17, The step of determining the signal quality, characterized in that to determine the jitter (bit error rate) (bER) according to the reproduction frequency deviation of the optical disk. The method of claim 12, The deviation of the jitter detected by the signal quality determining step is proportional to the reproduction frequency deviation of the optical disc. The method of claim 17, The area determination step is

Wherein the number of the areas is determined, wherein a is a difference between reproduction frequencies at the innermost and outermost circumferences of the optical disc, and n is the number of the areas. The method of claim 17, And the area determining step determines the number of areas divided in the optical disc and the boundary of the divided areas. The method of claim 17, Determining whether it is necessary to newly determine an area of the optical disk filtered by another cutoff frequency prior to the signal quality determining step, Wherein the signal quality determining step and the area determining step are performed when it is necessary to newly determine the area by the determining step. The method according to claim 16 or 17, And a cutoff frequency corresponding to the reproduction frequency deviation has different values in the determined plurality of regions. The method according to claim 16 or 17, And a cutoff frequency corresponding to the reproduction frequency deviation has the same value in a region where reproduction frequency deviations are similar among the determined plurality of regions. The method of claim 28, And the regions in which the reproduction frequency variations are similar are not adjacent to each other. The method according to claim 16 or 17, And wherein said filtering step performs low pass filtering at different cutoff frequencies on signals picked up optically from said determined plurality of regions, respectively. An optical disc reproducing apparatus for equalizing and reproducing a signal picked up optically from an optical disc, A control unit that divides the optical disk into a plurality of areas; And An equalizer configured to perform filtering at a predetermined cutoff frequency on signals picked up optically from the plurality of regions, And said predetermined cutoff frequency is different in adjacent areas. An optical disc reproducing method for equalizing and reproducing a signal picked up from an optical disc, Dividing the optical disc into a plurality of areas; And Filtering the signals picked up from the plurality of regions at a predetermined cutoff frequency, And said predetermined cutoff frequency is different in adjacent areas. A computer-readable recording medium having recorded thereon a program for executing an optical disk reproducing method of equalizing and reproducing an optically picked up signal from an optical disk, the method comprising: Determining how many regions the optical disc is to be divided according to the reproduction frequency deviation corresponding to the signal quality deviation to be limited; And And performing filtering on the determined plurality of regions at a cut-off frequency corresponding to the reproduction frequency deviation.

Images